Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Convertible Senior Notes Due March 2028 [Member]	Dec. 31, 2013 Convertible Senior Notes Due March 2028 [Member]	Mar. 31, 2014 Stock Options [Member]	Mar. 31, 2013 Stock Options [Member]
Earnings Per Share (Textual) [Abstract]
Number of shares of common stock equivalents related to convertible debt					2,071,279	780,421
Debt Instrument, Interest Rate, Stated Percentage			3.25%	3.25%
Basic EPS
Net income (loss) available to common stockholders	$ (37,191)	$ 12,270
Weighted average shares
Basic (in shares)	102,365,000	89,948,000
Effect of share based compensation plans (in shares)	0	88,000
Diluted (in shares)	102,365,000	90,036,000
Income (loss) per share
Basic (in dollars per share)	$ (0.36)	$ 0.14
Diluted (in dollars per share)	$ (0.36)	$ 0.14